[PATCH 2/4] KVM: MMU: support unsync sp out of the protection of'mmu_lock'

[Xiao Guangrong]

It allows keep unsync sp alive while it's out of the protection, later we can use
kvm_mmu_free_page() to free it if !sp->active_count

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
---
 arch/x86/kvm/mmu.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 839852d..4b7af3f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -996,7 +996,6 @@ static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
 	ASSERT(is_empty_shadow_page(sp->spt));
 	hlist_del(&sp->hash_link);
-	list_del(&sp->link);
 	__free_page(virt_to_page(sp->spt));
 	if (!sp->role.direct)
 		__free_page(virt_to_page(sp->gfns));
@@ -1681,9 +1680,8 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
 	kvm_mmu_unlink_parents(kvm, sp);
 	if (!sp->role.invalid && !sp->role.direct)
 		unaccount_shadowed(kvm, sp->gfn);
-	if (sp->unsync)
-		kvm_unlink_unsync_page(kvm, sp);
-	if (!sp->active_count) {
+
+	if (!sp->active_count || sp->unsync) {
 		/* Count self */
 		ret++;
 		list_move(&sp->link, invalid_list);
@@ -1692,6 +1690,8 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
 		kvm_reload_remote_mmus(kvm);
 	}
 
+	if (sp->unsync)
+		kvm_unlink_unsync_page(kvm, sp);
 	sp->role.invalid = 1;
 	kvm_mmu_reset_last_pte_updated(kvm);
 	return ret;
@@ -1709,8 +1709,12 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
 
 	do {
 		sp = list_first_entry(invalid_list, struct kvm_mmu_page, link);
-		WARN_ON(!sp->role.invalid || sp->active_count);
-		kvm_mmu_free_page(kvm, sp);
+		WARN_ON(!sp->role.invalid);
+		list_del(&sp->link);
+		if (sp->active_count)
+			WARN_ON(!sp->unsync);
+		else
+			kvm_mmu_free_page(kvm, sp);
 	} while (!list_empty(invalid_list));
 
 }
-- 
1.7.0.4

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